Liquid injection apparatus



Oct. 28, 1969 R. 1. HARRIS ET AL LIQUID INJECTION APPARATUS Filed Feb. 17. 1966 f it: t i El-:

lllllllllll United States Patent O 3,474,674 LIQUID INJECTION APPARATUS Rano J. Harris and Rano J. Harris, Jr., Baton Rouge, La.,

assignors to Precision Sampling Corporation, a corporation of Louisiana Filed Feb. 17, 1966, Ser. No. 528,201 Int. Cl. G01n 1/14 U.S. Cl. 73-422 9 Claims ABSTRACT OF THE DISCLOSURE An improved liquid injection apparatus comprising a movable plunger is mounted and slidable within the bore through a tubular member, and needle mounted on the forward end of said tubular member. The plunger per se is provided with a double-end forward capillary bore, an end of which extends from an orifice opening at the forward face of the plunger to an orifice opening the side of the plunger. Preferably, the forward end of the plunger is enlarged to form a capsule, and the double-end capillary bore is provided within the capsule. In such embodiment, the diameter or size of the forward portion of the needle is also stepped up or enlarged sufiiciently to house the capsule which can be extended outside the forward end of the needle, as for filling, or retracted into the enlarged needle opening for storage. Certain critical relationships are prescribed for the dimensions of the capillary bore, and capsule, relative to the enlarged needle opening.

This invention relates to the art of dispensing small accurately measured quantities or volumes of liquid, in reproducible quantities. In particular, it relates to new and improved liquid injection devices capable of high accuracy and precision.

The prior art defines various types of liquid injection devices including burets, needle syringes and other devices of the type wherein a barrel, provided with a needle on its forward or dispensing end is fitted with a mating plunger movable within the bore of the barrel or needle, or both, for withdrawal and dispensing of liquids. In the dispensing of liquids the plunger face generally abuts the liquid and positively dispels a measured quantity of liquid, or upon filling, withdrawal of the plunger permits displacement thereof with measured volumes of liquid for dispensing. Other types of liquid dispensing devices have included dippers, pipettes and the like wherein liquid in measured quantities were provided in sample cups, capillary openings for injection to a system, e.g. as to an analytical device. Many of these devices have proven of considerable merit, providing good accuracy, reprducibility and precision. Nevertheless, there is need in the art for new and improved devices capable of even higher precision and accuracy, especially where the liquids must be injected at high temperatures and pressures such as becomes necessary in injecting liquids into modern analytical devices or instruments.

The present invention contemplates improved apparatus for receiving, storing and dispensing liquids. The apparatus includes the combination of a capsule or member provided with capillary openings, including a forward opening and a side opening, and a contiguous outer closure member for sliding contact with the capsule to cover and uncover the side opening.

In a preferred form of the invention, the capsule is provided with a double end capillary bore, passageway or opening having a single forward orifice or opening and a single side orifice or opening to the exterior surface of the capsule. The contiguous outer closure member is preferably one which covers or encompasses the capsule, and at least a portion thereof, is in physical contact therewith ICC and movable relative thereto for covering and uncovering the side orifice or opening.

More preferably the capsule is a 1cylindrical member provided with a double-end capillary opening or passageway, opening or passageway extending from an orifice opening at the forward face of the cylindrical member, through a portion of the cylindrical member, to an orifice in the side of the cylindrical member. The closure member is an outer tubular member the inside diameter of which approximates or is slightly larger than the outside diameter of the cylindrical member, and the tubular member and cylindrical member are movable relative one in relation to the other so that the tubular member can be moved to cover the side opening of the capillary.

In accordance with the most preferred form of the present invention there is contemplated liquid injection apparatus comprising a hollow or tubular barrel, a hollow or tubular needle mounted at the forward end thereof, and a slidable mating plunger fitted through the axial opening or bore through the barrel and needle. A capsule or cylindrical member provided with a capillary chamber is located at the forward end of the plunger and is integral therewith so that the said chamber can be projected outside the needle for filling with liquid and then withdrawn into the needle for storage.

Preferably the chamber is a tubular opening of capillary size beginning at the face of the plunger, and terminating at the side of the plunger. Preferably also, an opening is located within the dispensing end of the needle which is of larger internal diameter than the opening through the tubular needle leading to the barrel, and the capsule or cylindrical member is of larger outside diameter than the diameter of the forward end of the plunger adjoined thereto, but lesser than the diameter of the enlarged needle opening at the dispensing end of the needle. Moreover, the length of the capsule or cylindrical member is less than the length of the opening within the dispensing end of the needle, and the difference in volume between that of the enlarged needle opening and the cylindrical member is at least about 2 times the volume of the capillary opening or chamber within the iylindrical member.

More preferably the volumetric difference between the volume occupied by the cylindrical member and the enlarged opening at the forward end of the needle ranges from about 2 times to about 100 times the volume of the capillary opening within the cylindrical member.

The invention will be better understood by reference to the following more detailed description and to the accompanying drawings to which reference is made as the present description unfolds.

In the drawings:

FIGURE l depicts an injection device, in partial section, in accordance with the preferred embodiment of the invention;

FIGURES 2 and 3 are fragmentary views of the forward portion of the device of FIGURE l showing in detail the novel feature wherein a slightly enlarged capsule or chamber with a double open end capillary opening for filling with an accurately measured quantity of liquid is mounted within or forms a portion of the forward end of a movable plunger, which chamber can be projected as for filling with liquid (FIGURE 3), or withdrawn into a receptacle or storage space located in the forward or dispensing end of the needle (FIGURE 2);

FIGURE 4 is another embodiment wherein the capsule or chamber is defined by a double end capillary opening in the forward end of a movable plunger of generally uniform diameter, which also fits into and can be stored within the dispensing end of the needle: and

FIGURE 5 shows a method of dispensing liquid from the capsule or chamber as e.g. in injecting liquid into a septum of an analytical instrument.

Referring specifically to FIGURE l of the drawings, is shown an injection device constituted generally of a hollow member or barrel 11-viz. a tube formed by an enclosing wall-having mounted at the forward end thereof a hollow or tubular needle 12. Needle 12 is pointed at the dispensing end 121 thereof and rigidly mounted within barrel 11 via extension through a central opening in tapered member or hub 13 and partially through a central opening through a packing 14. Hub 13 and packing 14 are tightly fitted within the confines of the enclosing tubular wall or shell which forms barrel 11.

Projected through a portion of the central opening through packing 14 from its opposite side is a tubular guide member 15. The opposite end of tubular guide member 15 is slidably coupled with an enclosing plunger guide member 21 which is projected through end wall 16 of barrel 11. The openings through guide member 15, packing 14 and needle 12 are contiguous and continuous, and form a passageway or bore running all the way through the central axis of the injection device 10. The bore is of uniform relatively large diameter through guide member 15, packing 14 and a portion of needle 12, but is of relatively smaller uniform diameter through most of needle 12, and up to the dispensing end of needle 12. A slidable plunger is itted into and conforms generally to the cross-sectional diameter of the bore. The back portion of the plunger 20 is of relatively large diameter and is freely movable within the bore through the guide 15, packing 14 and the entry portion of needle 12 lying within the hub 13. The immediate portion of plunger 20 is stepped down to mate with the smaller diameter opening through needle 12. The forward end of the plunger 20 is enlarged to form the capsule 30, this portion of the plunger 20 being retractable into the enlarged needle opening 32.

The plunger 20 is enclosed by a tubular plunger guide 21, the inside diameter of which approximates or is slightly larger than the external diameter of tubular guide member 15. Plunger guide member 21 tits over, mates with and is reciprocable upon tubular guide member 15 and as such provides for the support and alignment of plunger 20 within the bore of barrel 11. Both plunger 20 and plunger guide 21 are rigidly atiixed upon the handle 22 which serves as a convenient gripping means for application of force upon plunger 20.

The plunger guide member 21 of plunger 20 is provided with a stop 23 so that reverse movement of the plunger 20 is limited by impingement of the stop 23 with a projecting shoulder or surface 24 within barrel 11 and movement in the opposite direction (forward) is limited by contact of the shoulder 26 at the forward larger diameter portion of plunger 20 with the shoulder 25 of needle 12 near the end of barrel 11.

The forward end of the plunger 20 is provided with a capsule or cylindrical portion which can be of slightly larger external diameter than that of the forward portion of the plunger 20. The capsule or cylindrical member 30 is hollowed out to provide a liquid sampling capillary chamber 31 which can be totally filled in loading. In the specilic embodiment shown by reference to FIGURES 2 and 3, the forward end of plunger 20 is of tubular design, and is provided with an axial opening 29 beginning at the face of plunger 20. The opposite or terminal end of the tubular opening is side vented via opening 28 to provide a chamber 31 which is in effect a capillary bore with two open ends. The capillary opening or chamber 31 can be filled with liquid specimens by forward movement of plunger 20 to project the chamber outside of needle 12, as shown by reference to FIGURE 3. By touching the terminal or orilice end 29 of the chamber 30 to a liquid to be dispensed the chamber will till completely. The filling is automatic inasmuch as the capillary action draws the chamber full. The chamber can then be withdrawn back into the dispensing end 121 of needle 12 for storage, as shown by reference to FIGURE 2.

To dispense the liquid from the chamber 31 into an analytical instrument-viz. a gas chromatography or mass spectrometer, it is only necessary to press needle 12 into or project same through a septum. If the inner portion of the gas chromatograph or mass spectrometer is at sufficiently elevated temperature, volatization or gasification of the liquid will rapidly occur. The vaporizing liquid will exit from chamber 31 and will be forced backward by the instrument pressure into the annular opening between the cylindrical member and the internal or inside Wall around the dispensing end 121 of the needle 12. Upon further heating and expansion of the gas however, the gasied or volatized liquid will exit through the dispensing end 121 of needle 12 and will be carried via carrier gas into the analytical instrument.

It will be observed that the embodiment shown by reference to FIGURES 2, 3 differs from that shown by reference to FIGURE 4. In FIGURE 4 a capillary chamber 40 with capillary orlice openings 41, 42 are provided in the forward portion of the plunger 50. The plunger 50 is of generally uniform diameter and fits within a tubular needle 43. The diameter of the opening through needle 43 approximates or is only slightly smaller than the outside diameter of plunger 50. The forward portion or chamber 40 of plunger 50 is reciprocable into and out of the dispensing end 431 of tubular needle 43 for pickup, storage and ejection of measured quantities of liquid.

The preferred embodiment is shown by reference to FIGURES 1 3. In accordance therewith it will be observed that the capsule or cylindrical member 30 provides a total volume which is lesser than the volume of the opening 32 located at the forward or dispensing end 121 of needle 12. Thus, it will be observed that the outside diammeter of cylindrical member 30 is lesser than the internal diameter of opening 32. Moreover, the length of the opening 32 from wall 3 to the point 34 where the tip of needle 12 begins to taper is greater than the length of cylindrical member 30. Thus, there is a difference in the respective volumes. The volumetric difference, i.e. the difference in volume deiined by the volume of opening 32 (less the volume of that portion of the plunger 20 extending into the opening 32) and the volume of the chamber 31 of cylindrical member 30, constitutes a key and novel feature of the present invention. In accordance therewith, all or a portion of the vaporizing liquid to be injected will leave chamber 31 and fill this opening 32 prior to exit from the injection device 10` via dispensing end 121 of needle 12. Little or no vapor escapes around the annular space formed between the plunger 20 and the internal Wall surface of the needle 12, especially as occurs when a liquid specimen is injected into a very hot zone under considerable pressure.

In accordance with this embodiment the enlarged opening within the dispensing end 121 of needle 12 will be at least 2 times the volume of the chamber 31 of cylindrical member 30. The volume, however, can range up to about 1D0 times, and more preferably from about 10 to about 40 times, the volume of the chamber or capillary opening 31 wherein the liquid is initially contained. A volumetric capacity of l() times has been found to provide excellent benefits. Such volume assures adequate capacity to contain the vaporized liquid without substantial entrance of the vapors into the annular opening surrounding plunger 20.

Another method of injecting liquid from an injection device of this invention is shown by reference to FIG- URE 5. Thus, if e.g. the analytical instrument-viz. the gas chromatograph or mass spectrometer, is cold the capsule or cylindrical member or forward portion of plunger 50 containing chamber 40, as shown, can be thrust outwardly by forward movement of the plunger to project the chamber into or near the opening into the gas chromatograph or mass spectrometer, through which carrier gas and sample is conveyed into the instrument. This will tend to block the opening and reduce the flow of carrier gas therethrough, so that the pressure downstream of the opening will be reduced. Pressure upstream of the opening, however, will tend to be increased. Referring to FIGURE 5 is shown a needle 43 which has been thrust through septum 44 of a fiared conduit opening 45 leading into a chromatograph (not shown). Carrier gas enters conduit opening 45 via line 44 and normally enters the instrument via line 44. When entry 48 is blocked the carrier gas will thus exert pressure upon the vent side opening 41 of the chamber 40 and force the liquid from chamber 40 via opening 42 into the analytical instrument.

The injection device in its most preferred e-mbodiment is thus composed of four principal parts: a hollow or tubular barrel, a hollow or tubular needle rigidly mounted on the forward end thereof to provide a continuous bore through which is fitted a slidable mating plunger, a capsule with capillary openings for containing accurately measured quantities of liquid, the capsule being located at the forward end of the plunger for filling and storage within the dispensing end of the needle.

The barrel of the injection device can be made of substantially any material, metal alloys, steel, iron or the like. The plunger is composed of a resilient small diameter wire, stainless steel, tungsten, chrome, platinum alloy, or the like. The packing can be made of generally` conventional gasket materials, including rubber, neoprene, nylon, and the like but preferably is a self-lubricating type of packing, the polyliuoroethylenes of which constitute a preferred class. Polytetrauoroethylene, or Teflon (Dupont trademark for polytetrauoroethylene) is a highly preferred material and has been found to provide excellent results.

Having described the invention, What is claimed is:

1. In combination, liquid injection apparatus compris- 111g a tubular member,

a tubular needle mounted on the front end of the said tubular member,

an axial bore through the tubular needle and tubular member,

a plunger fitted into the axial bore,

a capsule formed by an enlarged forward portion of the plunger,

a stepped up opening in the forward end of the needle for containing the capsule when the plunger is retracted,

a double-end capillary bore located within the enlarged forward portion of the plunger which forms the capsule, an end of the bore extending through the plunger from an orifice opening at the forward face of the plunger to an orifice opening in the side of the plunger,

said plunger being movable within the axial bore so that the double-end capillary bore of the capsule can be extended outside the forward end of the tubular needle, vas for filling, and then retracted into the forward end of the tubular needle for storage.

2. The apparatus of claim 1 wherein the length of the capsule is less than the length of the opening within the forward end of the needle, and the difference in volume between the enlarged needle opening and th capsule is at least 2 times the volume of the double-end capillary opening within the capsule.

3. The apparatus of claim 2 wherein the difference between the volume of the enlarged needle opening and capsule is from about 2 to about 100 times the volume of the double-end capillary opening within the capsule.

4. The apparatus of claim 2 wherein the difference between the volume of the enlarged needle opening and capsule is from about to about 40 times the volume of the double-end capillary opening within the capsule.

5. In combination, liquid injection apparatus comprislug a barrel,

a hub having a central opening mounted on the forward end of the barrel,

a tubular packing located adjacent to and behind the hub,

a tubular needle mounted at the forward end of the barrel, by extension of said needle through the hub,

and at least partially through the packing,

an axial bore extending through the said needle, hub

and packing,

a slidable mating plunger fitted into the axial bore extending through the said needle, hub and packing,

an opening -at the dispensing end of the needle which is contiguous to and of larger internal diameter than the axial bore extending through the said needle, hub and packing,

a cylindrical member adjoined to the forward end of the plunger, said cylindrical member being of larger outside diameter than that of the adjoining plunger, a double-end capillary bore within said cylindrical member, an end of the bore extending through the cylindrical member from an orifice opening at the forward face thereof to an orifice opening in the side of the said cylindrical member,

said cylindrical member having a cross-sectional diameter less than the cross-sectional diameter of the opening at the dispensing end of the needle, and a length less than the length of the opening Within the dispensing end of the nedle,

ths difference in volume between the said enlarged needle opening and the cylindrical member at least about 2 times the volume of the capillary opening within the cylindrical member,

so that when the double-end capillary bore is extended outside the dispensing end of the tubular needle, filled with liquid, and then retracted into the dispensing end of the tubular needle for storage, such differential volume assures adequate capacity to contain the liquid, even when vaporized, without substantial entry thereof into the annular opening surrounding the plunger.

6. The apparatus of claim 5 wherein the packing is Teflon.

7. 'Ihe apparatus of claim 5 wherein the apparatus is also provided with a plunger guide which consists of tubular member, the bore of which is aligned upon the bore through the needle, hub and packing, and with which is also contained the slidable plunger.

8. The apparatus of claim 5 wherein the volumetric difference between the volume occupied by the cylindrical member and the enlarged opening at the forward end of the needle ranges from about 2 times to about 100 times the volume of the capillary opening within the cylindrical member.

9. The apparatus of claim 8 wherein the volumetric difference between the volume occupied by the cylindrical member and the enlarged opening at the forward end of the needle ranges from about 10 times to about 40 times the volume of the capillary opening within the cylindrical member.

References Cited UNITED STATES PATENTS 2,643,801 6/ 1953 Kollmeyer 222-420 2,991,647 7/ 1961 Harris.

3,252,331 5/ 1966 Lancaster.

3,313,299 4/ 1967 Spademan 12S-214.4 3,335,723 8/1967 Waldman 128-214.4

LAVERNE, D. GEIGER, Primary Examiner E. J. EARLS, Assistant Examiner U.S. Cl. X.R. 73-425 .4 

